Pressure-reducing valve

ABSTRACT

A pressure-reducing valve for obtaining a constant low-pressure flow of high volume of fluid which is supplied to the valve under high pressure. The valve comprises a pair of axially movable pistons connected by a rod within a valve-housing cylinder. The cylinder is closed at one end and a spring acts on free end of the piston assembly for urging the piston away from the closed end. The other end of the cylinder is provided with an outlet port through which the low-pressure fluid is passed from the valve and an inlet port is provided in the sidewall of the cylinder for introducing high pressure fluid to a space between the pistons. The piston assembly is hydrostatically journaled within the cylinder and is provided with a plurality of axially extending slits which vary in passageway size by the relative position of the piston within the cylinder. The high-pressure fluid is passed through the slits to a chamber on the other side of the piston and then through a turbulent-producing orifice to the outlet port.

United States Patent Hillebrand Johannes Josephus Kraakman Emmasingel,Eindhoven, Netherlands [72] Inventor [21] Appl. No. 856,635 [22 FiledSept. 10, 1969 [45] Patented Aug. 3, 1971 U. 5. Philips Corporation NewYork. .1.

[32] Priority Sept. 18, 1968 [3 3] Netherlands [73] Assignee [54]PRESSURE-REDUCING VALVE 5 Claims, 1 Drawing Fig.

[52] US. Cl 137/501, 251/324 [51] Int. Cl G05d 7/01 [50] Field of Search137/501 Assistant ExaminerR. B. Rothman Atwmey- Frank R. TrifariABSTRACT: A pressure-reducing valve for obtaining a constantlow-pressure flow of high volume of fluid which is supplied to the valveunder high pressure. The valve comprises a pair of axially movablepistons connected by a rod within a valve-housing cylinder. The cylinderis closed at one end and a spring acts on free end of the pistonassembly for urging the piston away from the closed end. The other endof the cylinder is provided with an outlet port through which thelow-pressure fluid is passed from the valve and an inlet port isprovided in the sidewall of the cylinder for introducing high pressurefluid to a space between the pistons. The piston assembly ishydrostatically journaled within the cylinder and is provided with aplurality of axially extending slits which vary in passageway size bythe relative position of the piston within the cylinder. Thehigh-pressure fluid is passed through the slits to a chamber on theother side of the piston and then through'a turbulent-producing orificeto the outlet port.

PATENTED AUG 3 I971 INVIENTOR. HILLEBRAND J.J. KRAAKMAN AGENTPRESSURE-REDUCING VALVE The invention relates to a pressure-reducingvalve for obtaining a constant, low-pressure flow of large volume ofmedium supplied to the valve under a high pressure. The density of themedium is substantially independent from the pressure. An inletconnection for the medium under pressure is provided in the wall of thecircumference of a cylinder which is closed at one end. An outletconnection for conducting away the medium is provided in the opensidewall of the cylinder.

It is the object of the invention to obtain a pressure-reducing valvewhich can regulate a large quantity of medium in which the pressure ofthe supplied medium can be a few tenths of atmospheres while the volumeof the flow which emerges from the valve should be constant independentof said pressure. For that purpose, a pressure-reducing valve accordingto' the invention as described above is characterized in that ahydrostatically or pneumostatically journaled and axially movable pistonis provided in the cylinder and is spring-loaded on one side limiting afirst chamber on which side also the pressure of the supplies mediumacts, the other side of the piston limiting a second chamber whichcommunicates, through a gap which allows only passage of a turbulentflow, with the outlet connection. The circumference of the piston isprovided with axially extending slits which provide a variable passagedetermined by the position of the piston for the medium from the firstchamber to a groove in the cylinder wall which is in open communicationwith the second chamber.

In order to improve the bearing and to obtain a better surface ofengagement for the spring as well as a better defined pressure surfaceon the piston, according to an embodiment of the invention a secondpiston, also hydrostatically or pneumostatically journaled, is presentwhich is rigidly secured to the first piston by means of a piston rod,the first chamber being situated between said pistons and the springpressing on a sidewall of the second piston.

The flow conditions in the valve and the operation are further improvedif, according to a further embodiment of the invention, the bottom ofthe slits at the area where they open into the groove in the cylinderwall, is streamlined and the transition angle to the cylinder and thegroove wall corresponding therewith encloses an angle of approximately60 with the centerline of the cylinder.

in order to further improve the dynamic stability of the piston,according to another embodiment of the invention, a duct having a fixedresistance is present between the outlet connection of the medium andthe space in which the spring is situated.

ln order that the invention may be readily carried into effect, oneembodiment thereof will now be described in greater detail, by way ofexample, with reference to the accompanying drawing, the FIGURE of whichis a cross-sectional view of a= pressure reducing valve.

in the drawing, reference numeral 1 denotes a cylinder which is closedat one end by a cover 2 and in which a piston assembly consisting of twopistons 3 and 4, connected by a rod 5 is axially movable. The piston 3has a groove 6, and a spring 7 presses at one end thereof against piston3 and bears against the cover 2 on its other side. On its circumferencethe piston 4 comprises a number of shallow bearing chambers 8 and anumber of shallow bearing chambers 9, as well as four slits 10. Thebottom of these slits 10 is streamlined at its end and finally enclosesan angle of approximately 60 with the cylinder wall. This wall comprisesa circumferential groove 11, having a trapezoidal cross section, oneside of said trapezoid extending at right angles to the cylinder walland the other side also enclosing an angle of approximately 60 with thewall. The piston 4 comprises a chamber 12 which communicates, through anaperture 13, both with a gap 23 between the piston 4 and the cylinderwall and with the groove 11. Moreover, an open duct 14 extends from thepiston 3 through the rod 5 to and through the piston 4 to chamber 12;the groove 6 communicates with said duct through an aperture 15.

Bearing chambers 8 communicate with the space between the pistons 3 and4 through apertures 16 and chambers 9 communicate with slits 10 throughapertures 17. An opening 24 for the supply of a medium, is present inthe cylinder 2 between the pistons 3 and 4. Behind the piston 4 in thecylinder an aperture 18 is present which is bounded by sharply taperingwalls 19. Behind this aperture, an opening 20 is present for the outletof the medium. A duct 21 communicates the space 20 with the spacebetween the piston 3 and the cover 2; in this duct a resistance 22 ispresent.

The device shown illustrates a pressure-reducing valve for obtaining aconstant low-pressure flow of large volume of medium which is suppliedunder a high pressure to the device. The density of this medium is onlyslightly dependent upon, or totally independent of the pressure. Thefluids are liquids and some gases, so that the flow is constant. Thepressure may be a few tenths or even hundreth of atmospheres. Bothpistons are journaled hydrostatically; the piston 3 only serves as apressure surface for the spring 7and to obtain a better guiding of thepiston assembly. Any. leakflow along said piston is conducted awaythrough thezg'roove 6, aperture 15 and duct 14.

When the medium under high pressure enters the space between the pistons3 and 4, it .will escape through the slits 10 to the groove 11 andthence through aperture 13 to chamber 12. The aperture l8'with thebounding wall 19 are constructed so that a turbulenttemperature-independent flow occurs in the aperture 18. Owing to thevolume of the groove 11 which is large in relation to the cross sectionof the slits 10 a pressure reduction of the medium occurs, while owingto the pressure relation between the pressure which prevails in thespace between the pistons 3 and 4, and the pressure in the chamber 12,the piston assembly moves more or less axially in accordance with theforce of thespring 7, which preferably must have a constant stiffness;as a result of this movement a larger or smaller part of the outlet sideof the slits 10 comes in open communication with the groove 11. in thebearing chambers 8 which communicates with the high-pressure spacebetween the pistons through apertures 16, a comparatively high pressureprevails; any leak flow of the gap between the piston and the cylinderwall is conducted away to the slits 10 through chambers 9 and aperture17. The duct 21 having resistance 22 only serves to further improve thedynamic stability of the as sembly; this duct with resistance 22 is notalways necessary.

The device according to theinvention shown serves to regulate largequantities of medium which may be under a high pressure. Moreover, thedevice can very simply and easily be manufactured and gives very goodresults in practice.

What we claim is:

l. A pressure-reducing valve for obtaining constant low pressure flow oflarge volume of medium, the density of said medium being independent of.the pressure applied thereto comprising, a cylinder forming a valvehousing being closed at one end thereof, inlet means through thecircumferential wall of said cylinder for supplying medium underpressure to said valve, outlet means through an end wall of saidcylinder for passing medium away from said valve, first and secondpistons hydrostatically journaled for axial movement within saidcylinder, a piston rod connecting said first piston to said secondpiston, a first chamber formed between the inner end faces of said firstand second pistons, said inlet means communicating with said firstchamber so that medium under pressure is supplied thereto, a secondchamber formed between the outer end face of said first piston and anorifice, said orifice communicating with said outlet means forpermitting turbulent flow of medium from said second chamber to saidoutlet, a circumferential groove on the inner wall of said cylinder,said groove being in open communication with said second chamber, aplurality of axially extending slits provided on the surface of saidfirstpiston for passing medium from said first chamber to said groove,the amount of available passageway through said slits being variabledepending upon the axial position of said piston, a compression springwithin a third chamber acting on the outer end face of said secondpiston, a

duct within the cylinder wall communicating, between saidoutlet meansand said third chamber, and a restriction within said duct.

2. A pressure-reducing valve for obtaining constant lowpressure flow ofmedium comprising a valve housing being closed at one end thereof, anoutlet port located at the other end, an inlet port located in asidewall of said housing for supplying medium under pressure to saidvalve, piston means hydrostatically journaled for axial movement withinsaid housing, a compression spring acting on one side of said pistonmeans for urging said piston means away from said closed end, a firstchamber communicating with said inlet port so that medium under pressureacts on said piston means, a second chamber formed between the otherside of said piston means and said outlet port, an orifice for producingturbulent flow therethrough communicates between said second chamber andsaid outlet port, a groove in the inner surface of said housing in opencommunication with said second chamber, a plurality of slitslongitudinally extending along the circumferential surface of saidpiston means, said slits communicating with said groove and providing avariable size passageway for said medium thereto, the size of saidpassageway dependent upon the position of said piston means within saidhousing.

3. The pressure reducing valve according to claim 2 wherein said pistonmeans comprises a pair of pistons, a rod connecting said pair ofpistons, said first chamber being formed between said pair of pistons,and said spring acting on the free end face of one of said pistons.

4. The pressure-reducing valve according to claim 3 wherein said slitshave a streamlined bottom surface, said slits having a transitionportion at the point of communication with said groove, said transitionportion forming an angle of 60 with respect to the longitudinal axis ofsaid pistonl 5. The pressure-reducing valve according to claim 4 furthercomprising a duct in the valve-housing body communicating at one endthereof with said outlet and at the other end thereof with the space inwhich said spring is located, and a restriction within said duct.

1. A pressure-reducing valve for obtaining constant low-pressure flow oflarge volume of medium, the density of said medium being independent ofthe pressure applied thereto comprising, a cylinder forming a valvehousing being closed at one end thereof, inlet means through thecircumferential wall of said cylinder for supplying medium underpressure to said valve, outlet means through an end wall of saidcylinder for passing medium away from said valve, first and secondpistons hydrostatically journaled for axial movement within saidcylinder, a piston rod connecting said first piston to said secondpiston, a first chamber formed between the inner end faces of said firstand second pistons, said inlet means communicating with said firstchamber so that medium under pressure is supplied thereto, a secondchamber formed between the outer end face of said first piston and anorifice, said orifice communicating with said outlet means forpermitting turbulent flow of medium from said second chamber to saidoutlet, a circumferential groove on the inner wall of said cylinder,said groove being in open communication with said second chamber, aplurality of axially extending slits provided on the surface of saidfirst piston for passing medium from said first chamber to said groove,the amount of available passageway through said slits being variabledepending upon the axial position of said piston, a compression springwithin a third chamber acting on the outer end face of said secondpiston, a duct within the cylinder wall communicating between saidoutlet means and said third chamber, and a restriction within said duct.2. A pressure-reducing valve for obtaining constant low-pressure flow ofmedium comprising a valve housing being closed at one end thereof, anoutlet port located at the other end, an inlet port located in asidewall of said housing for supplying medium under pressure to saidvalve, piston means hydrostatically journaled for axial movement withinsaid housing, a compression spring acting on one side of said pistonmeans for urging said piston means away from said closed end, a firstchamber communicating with said inlet port so that medium under pressureacts on said piston means, a second chamber formed between the otherside of said piston means and said outlet port, an orifice for producingturbulent flow therethrough communicates between said second chamber andsaid outlet port, a groove in the inner surface of said housing in opencommunication with said second chamber, a plurality of slitslongitudinally extending along the circumferential surface of saidpiston means, said slits communicating with said groove and providing avariable size passageway for said medium thereto, the size of saidpassageway dependent upon the position of said piston means within saidhousing.
 3. The pressure reducing valve according to claim 2 whereinsaid piston means comprises a pair of pistons, a rod connecting saidpair of pistons, said first chamber being formed between said pair ofpistons, and said spring acting on the free end face of one of saidpistons.
 4. The pressure-reducing valve according to claim 3 whereinsaid slits have a streamlined bottom surface, said slits having atransition portion at the point of communication with said groove, saidtransition portion forming an angle of 60* with respect to thelongitudinal axis of said piston.
 5. The pressure-reducing valveaccording to claim 4 further comprising a duct in the valve-housing bodycommunicating at one end thereof with said outlet and at the other endthereof with the space in which said spring is located, and arestriction within said duct.